In the production of manganese activated zinc silicate phosphors, excess silicic acid with long blending times are used with fluxes and long firing times in order to achieve a good reaction. This phosphor requires a high manganese concentration that is necessary for high luminescence efficiency and it is difficult to achieve a good blend especially with the zinc component. Sometimes this phosphor manufactured by these methods results in a brown or yellow discoloration and very poor fluoroescent lamps. This is due possibly to minute traces of unincorporated manganese with the unreacted zinc component.